Marine life  /  Triggerfish & filefish  /  Orange-lined triggerfish
Reviewed 2026-09-06
Species entry

Orange-lined triggerfish

Balistapus undulatus

Dark green ruled with orange curves, and territorial enough to follow a diver off its patch.

Size
To 30 cm
Depth
2–45 m
Habitat
Reef slopes
Active
Daylight
Range
Indo-Pacific
Rarity
Bali
1 star of 5, found on most dives
SP-01
orange-lined triggerfish · full body · habitat
4:3 · min 2400px

To about 30 cm, dark green to olive with curved orange-yellow lines running back from the head across the flanks, an orange band from the mouth to the pectoral fin, and a yellow tail. Mature males lose the lines on the snout. It is the most brightly marked of the common triggerfishes here and is not readily confused with anything else.

Like all triggerfishes it locks the first dorsal spine upright with the second to wedge itself into a crevice. It feeds on urchins, molluscs, coral and algae, and is aggressive towards other fish over food. Territorial individuals will approach and follow a diver, and while the species is far smaller than the titan triggerfish it is quicker to react. Recorded from about 2 to 45 m.

Where to find:

LocationRarity Best monthsDepthHabitat
Bali Indonesia editorial estimate
1 star of 5, found on most dives
Year-round
2–45 m
Reef slopes
Papua New Guinea Papua New Guinea editorial estimate
1 star of 5, found on most dives
Year-round
2–45 m
Coral reef and slopes
Lembeh Strait Indonesia editorial estimate
2 stars of 5, usually seen in a week
Year-round
2–40 m
Coral reef, rubble and reef slopes
Anilao Philippines editorial estimate
2 stars of 5, usually seen in a week
Year-round
2–40 m
Coral reef and rubble
Dauin & Dumaguete Philippines editorial estimate
2 stars of 5, usually seen in a week
Year-round
2–35 m
Reef edges and rubble

Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.

Related species

SP
arabian picassofish
16:10
Arabian picassofish
Rhinecanthus assasi
SP
barred filefish
16:10
Barred filefish
Cantherhines dumerilii
SP
black durgon
16:10
Black durgon
Melichthys niger
SP
blue triggerfish
16:10
Blue triggerfish
Pseudobalistes fuscus